Superconductivity in potassium-doped metallic polymorphs of MoS2

Superconducting layered transition metal dichalcogenides (TMDs) stand out among other superconductors due to the tunable nature of the superconducting transition, coexistence with other collective electronic excitations (charge density waves) and strong intrinsic spin-orbit coupling. Molybdenum disulphide (MoS2) is the most studied representative of this family of materials, especially since the recent demonstration of the possibility to tune its critical temperature, Tc, by electric-field doping. However, just one of its polymorphs, band-insulator 2H-MoS2, has so far been explored for its potential to host superconductivity. We have investigated the possibility to induce superconductivity in metallic polytypes, 1T- and 1T'-MoS2, by potassium (K) intercalation. We demonstrate that at doping levels significantly higher than that required to induce superconductivity in 2H-MoS2, both 1T and 1T' phases become superconducting, with Tc = 2.8 and 4.6K, respectively. Unusually, K intercalation in this case is responsible both for the structural and superconducting phase transitions. By adding new members to the family of superconducting TMDs our findings open the way to further manipulate and enhance the electronic properties of these technologically important materials.Comment: 13 pages, 5 figures plus 7 supplementary figures in Nano Letters, November 27, 201

Unusual suppression of the superconducting energy gap and critical temperature in atomically thin NbSe2

It is well known that superconductivity in thin films is generally suppressed with decreasing thickness. This suppression is normally governed by either disorder-induced localization of Cooper pairs, weakening of Coulomb screening, or generation and unbinding of vortex-antivortex pairs as described by the Berezinskii-Kosterlitz-Thouless (BKT) theory. Defying general expectations, few-layer NbSe2 - an archetypal example of ultrathin superconductors - has been found to remain superconducting down to monolayer thickness. Here we report measurements of both the superconducting energy gap and critical temperature in high-quality monocrystals of few-layer NbSe2, using planar-junction tunneling spectroscopy and lateral transport. We observe a fully developed gap that rapidly reduces for devices with the number of layers N < 5, as does their ctitical temperature. We show that the observed reduction cannot be explained by disorder, and the BKT mechanism is also excluded by measuring its transition temperature that for all N remains very close to Tc. We attribute the observed behavior to changes in the electronic band structure predicted for mono- and bi- layer NbSe2 combined with inevitable suppression of the Cooper pair density at the superconductor-vacuum interface. Our experimental results for N > 2 are in good agreement with the dependences of the gap and Tc expected in the latter case while the effect of band-structure reconstruction is evidenced by a stronger suppression of the gap and the disappearance of its anisotropy for N = 2. The spatial scale involved in the surface suppression of the density of states is only a few angstroms but cannot be ignored for atomically thin superconductors.Comment: 21 pages, including supporting informatio

Organisation and Governance of Urban Energy Systems:District Heating and Cooling in the UK

International audienc

One-dimensional proximity superconductivity in the quantum Hall regime

Extensive efforts have been undertaken to combine superconductivity and the quantum Hall effect so that Cooper-pair transport between superconducting electrodes in Josephson junctions is mediated by one-dimensional (1D) edge states. This interest has been motivated by prospects of finding new physics, including topologically-protected quasiparticles, but also extends into metrology and device applications. So far it has proven challenging to achieve detectable supercurrents through quantum Hall conductors. Here we show that domain walls in minimally twisted bilayer graphene support exceptionally robust proximity superconductivity in the quantum Hall regime, allowing Josephson junctions operational in fields close to the upper critical field of superconducting electrodes. The critical current is found to be non-oscillatory, practically unchanging over the entire range of quantizing fields, with its value being limited by the quantum conductance of ballistic strictly-1D electronic channels residing within the domain walls. The described system is unique in its ability to support Andreev bound states in high fields and offers many interesting directions for further exploration

Successful sales practices employed by Canadian high-tech start- ups: findings from five case studies

Le texte intégral de ce document de travail n'est pas disponible en ligne. Une copie papier est disponible à l'Annexe de la bibliothéque. Effectuez une recherche par titre dans le catalogue pour réserver le document. // The full text of this working paper is not available online. A print copy is available in the Library Annex. Search by title in the catalogue to request the paper

An Investigation into Self-Translation

The paper analyzes the nature, basic aspects, and specific features of self-translation in the context of translation theory and practice, as well as basic causes making writers translate their works. The analysis of the works on the topic shows that the issue is understudied and demands further investigation. Our analysis shows that self-translation (translation of the author) is considered to be the translation of an original work into another language by the author himself. On the one hand, it is a rather rare phenomenon. On the other hand, self-translation represents “ideal” translation since the author is in a better position than any ordinary translator because he knows his creation as nobody else and has the authority to allow himself shifts in the translation which might not have been ‘allowed’ by another translator. The results of self-translation can be regarded as certain “gold standards” for others to make use of. There are different reasons that cause bilingual writers to translate their works, both linguistic (interest to languages, wish to create and use new expressive means, dissatisfaction with existing translations, etc.) and extra-linguistic (emigration, challenge to check one’s gift in new conditions, paying tribute to motherland, etc.). It is obvious that some reasons are objective, but others can be considered subjective, the latter being more powerful and stimulating

Tribes, politics and social change in India A case of the Mullukurumbas of the Nilgiri Hills

SIGLEAvailable from British Library Document Supply Centre- DSC:DXN002363 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Technology of physical and coordination-technical improvement of firefighters and rescuers in training activities

The study defines pedagogical conditions that contribute to the growth of sports skills of men 19-23 years old, competing in fire and rescue sports. The conditions provide knowledge of the competitive activity laws implementation. The procedural and effective methods that solve the problems of developing physical and improving coordination and technical training of fire and rescue workers, introduce a differentiated approach to training athletes, taking into account the revealed competitive typology and predisposition to successful performance in certain applied disciplines of the sport. The model characteristics of athletes aged 19-23 years competitive activity are determined; individual and group typological features of sports performance in competitions are revealed and a differentiated approach to physical training of firefighters and rescuers is justified. The technology of combined physical and coordination-technical improvement of athletes aged 19-23 years in fire and rescue sports is developed based on the algorithm of training actions sequential change. The methodology of fire-rescue professional development is proved. There the leading party application process became sports and training activities with the use of firerescue sports. The method of training men-juniors 19-20 years old and young athletes 21-23 years old to participate in competitions in fire-rescue sports is developed. We used pedagogical experiment, pedagogical testing; instrumental methods; methods of mathematical statistics